### The Learning Journey

Presentation on our journey

Circuit Design
A circuit has a few important and basic components . There is the power source , the wires , resistors and the output source ( eg . A light bulb ) . In circuit design , we have to try to rearrange all these components so that the circuit draws the least energy .
Terminologies

 Terms Description Unit of measurement Charge A quantity Coulomb (Q) Current Rate of flow of electric charge . If charge particles were to move from point A to B , current would be the number of particles passing through point B per second . Amperes (A)ORCoulomb/sec Voltage The energy causing the current / the electric particles to move Volts (V) Resistance Restricts how much current flows through Ohms (Ω)
***Important to note :
The Ohms law is the basic law that governs the whole world of electronics . It describes the relationship between Current , Voltage and Resistance .
Ohms law :
V = I x R
In which , V = Voltage , I = Current and R = resistance .
Equipments and Components

 A Voltage source with its different parts
1. Voltage Source
This basically converts the AC from the power sockets into DC as the circuit that we are going to build can only work on DC . There are various knobs for us to adjust the voltage , either in big or small intervals . There are also other knobs and buttons , as seen in the picture on the right .

2. Multimeter
 A multimeter with its different parts

This instrument is used to measure Voltage , Current and Resistance .
It is purely for measurement so it does do affect the circuit in any way .

2.1 Measuring Voltage with a Multimeter
 Measuring voltage
Before anything , check and make sure that the Multimeter is set to the voltage measurement . When measuring Voltage with a Multimeter , everything must be done in a PARALLEL arrangement . For example ,to find out the potential voltage difference between a specific location of the circuit and the ground ( powers source ) , the positive terminal would have to be connected to the desired location and the negative to the ground . However , if the voltages of the two leads are known , then the negative terminal would be connected to the lead with the lower voltage while the positive terminal is connected to the lead with a higher voltage .

2.2 Measuring Current with a Multimeter
 Measuring Current
Before anything , check and make sure that the Multimeter is set to the current/resistance measurement . When measuring current , everything must be arranged in a SERIES arrangement . When the Multimeter is used as an ammeter , it has a very small impedance ( resistance ) and will result in a small voltage drop across the multimeter’s leads.

 Measuring Resistance
2.3 Measuring Resistance with a Multimeter
Before anything , check and make sure that the Multimeter is set to the current/resistance measurement . When measuring resistance , everything must be arranged in a PARALLEL arrangement . To measure resistance across a resistor , connect the positive terminal on either one end of the lead and the negative terminal on the other end lead .

 Standard EIA Color Code Table

 A resistor , as compared to a handphone

3. Resistors

This component resists the flow of electrical current . The voltage of the current is dropped as it flows through one terminal to the next terminal of the resistor . Resistors add the safety element to the circuit as it maintains a known safe current for the circuit . Resistance is measured in ohms . A high ohm rating means a high resistance to current . Because resistors are so small , colour bands are imprinted on the resistors itself which allows us to tell the ohm rating of that resistor . The bands are de-coded using the ‘ Standard EIA Color Code Table ‘ .

4. Transistor
It is basically a switch that is activated on the voltage/current it receives . The transistor connects circuits from its “c” terminal to the circuits attached to its “E” terminal depending on the voltage/current applied to its “B” terminal . If the voltage/current is high , the switch is turned ON . Otherwise , it is OFF .

5. Light Dependent Resistor (LDR)
LDR or photoconductor is a resistor with varying resistance according to light intensity . For this particular LDR , resistance decreases when light intensity increase .

6. Force Sensitive resistor (FSRs)
FSRs are resistors with varying resistance according to force applied . The resistance of the FSR decreases when the the force increases .

7. Potentiometer / Rheostat
It is a three-terminal resistor . The dial on the Potentiometer is mechanically rotated to determine the resistance . Rheostat is used to adjust volume while a Potentiometer is used to adjust the brightness of lamps .

8. Light Emitting Diode (LED)
LED is a special semiconductor that convert light directly from electricity . We used this in our circuits to check on whether there is current flowing through the circuit .

It is a construction base for prototypes . It is useful for experimenting as no soldering is required and is reusable . This give us room for us to make mistakes . Refer to picture on the side for the breadboard connection .
9.1 Resistors in Parallel on Breadboard

9.2 Resistors in Series

Experiments
1: Knowing the Voltage Source and multimeter
What we got out of this experiment was how to use the voltage source as well as the multimeter . We had to fine tune on the Voltage source in order to get those smaller voltages such as 1V . To measure with the multimeter we had to make sure that the arrangement was parallel .
2: Knowing the resistance - colour codes
We learnt how to read the bands on the resistor in this experiment .
The resistor that we got was one with Brown , Black , Orange and Gold bands , in respective orders .
So , referring to the table , we derived that the resistance was  :
[ ( 10 x 10³ ) x ±5% ] ohms
= ( 10 000 ± 500 ) ohms
3 : Knowing the Ohm’s Law
We learnt how to manipulate the Ohm’s Law , which means shifting the values around to find what we want . In this experiment , with an un-changed resistor , the current increased as the voltage increased .
4: Knowing the Series and parallel connections of resistors
Through this experiment , we discovered how to find out the total resistance of several resistors in both parallel and series connections .
For Series connection ,
R1 + R2 = R
For Parallel connection ,
RT = R1R2 / R1+R
We also realised that these two equations could be derived from the Ohm’s Law.
5-8 : Connecting the LED , Transistor , FSR and LDR in circuits
For these few experiments , we learned how to successfully connect these componenets in a circuit  and also learn how each component worked .